<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div {
            height: 3em;
            background-color: green;
        }

        span {
            font-size: 40px;
            padding: 200px;
            background-color: red;
            margin: 100px;
            position: absolute;
            left: 100px;
            top: 100px;
        }
    </style>
    <script>
        var a = 100;
        var b = 200;
        var temp;
        tmp = a;
        a = b;
        b = tmp;
        console.log("a = " + a);
        console.log("b = " + b);
        var num = 2.3;
        console.log(typeof (num));
        console.log(typeof (y));
        var cc = parseFloat("12.3Ff");
        console.log(cc)
        var dd = parseFloat("ddfa232F");
        console.log(dd);
        var  mm = "hello world";
        console.log(mm);
        var mc = 1;
        var ccv = mc++ + ++mc;
        console.log(ccv);
        var maxValue = Number.MAX_VALUE;
        var cmk = maxValue * 2;
        console.log(cmk);
        var kkk = "23";
        var kkkk = kkk  * 2;
        console.log(kkkk);
        var ko = Number("3324");
        console.log(ko);
        var s = String(122);
        console.log(s);
        console.log(typeof s);
        var ff = 3 > 2 && 5 < 3;
        console.log(ff);
        var dd = 239 && 989;
        console.log(dd);
        var cc = 239 || 989;
        console.log(cc);

    </script>
</head>
<body>
<input type="button" value="button" onclick="alert('hello javscirpt')">
</body>
</html>